Five or more short blasts on a vessel’s whistle indicates that she is（）.

（）is a computer technology that headsets,sometimes in combination with physical spaces or multi-projected environments,to generate realisitic images,sounds and other sensations that simulate a user’s physical presence in a virtual or imaginary environment.

Air or noncondensable gas is removed from a refrigeration system by a （）

（ ）Is red a strong color or a peaceful color?

Project（71）is an uncertain event or condition that，if it occurs，has a positive or a negative effect on at least one project objective，such as time，cost，scope，or quality．

Project ______is an uncertain event or condition that，if it occurs，has a positive or a negative effect on at least one project objective，such as time，cost，scope，or quality．

● Project（71）is an uncertain event or condition that, if it occurs, has a positive or a negative effect on at least one project objective, such as time, cost, scope, or quality.（71）

 ______ twice a year, whether it is a car or a bus or a truck, is the rule that every driver must obey in this city.

（ ）estimating is a technique for estimating the duration or cost of an activity ou project using historical data from a similar activity or project.

A mark or place at which a vessel comes under obligatory entry，transit，or escort procedure is know as（）.

The third officer’s duty is to（）when vessel is commanded under the pilot or captain.

（）generally indicates that a gale or storm is approaching.